1. TECHNICAL FIELD
The present invention relates, in general, to a cornea storage device and, in particular, to a cornea retainer which holds isolated donor corneas in a specific orientation during storage.
2. BACKGROUND INFORMATION
At present, penetrating keratoplasty for restoring sight in patients with cornea opacity is highly successful. However, the quantity of surgical-quality donor corneas is in short supply. The number of available corneas is determined by a combination of two factors: (1) the length of time between the death of the donor and the preservation of the cornea, and (2) the length of time that the donor cornea is stored. Presently, procurement of donor corneas no more than 12 hours after death and storage for no more than 72 hours constitute the guidelines for the distribution of donor tissues for transplant. Donor corneas with a preservation time of up to 96 hours are used on an emergency basis.
The development of methods for extending the time donor corneas may be stored has significant clinical implications as well as marketing potential. Extending corneal preservation time increases the quantity of tissues available for transplant, provides surgeons flexibility in performing operations, improves scheduling of elective surgery, and affords more cost efficient use of operating rooms. Patients benefit from enhanced physiological quality of donor corneal tissue.
Presently, isolated human donor corneas are stored in vials containing Medium 199 supplemented with 5% dextran or 2% chondroitin sulfate. An isolated cornea stored in this manner may settle to the bottom of the storage vial with the endothelium-side facing up or down. Under these storage conditions, the medium immediately surrounding the cornea may contain elevated levels of metabolic wastes and insufficient levels of corneal nutrients. When the endothelium faces the bottom of the storage vial, the problems of waste accumulation and nutrient depletion are enhanced. The metabolic activity (an indicator of tissue viability) of corneas subjected to these storage conditions decreases rapidly.
In addition to the deleterious chemical environment surrounding corneas stored according to current protocols, the present storage method also subjects donor tissue to adverse physical conditions. The surface of the corneal tissue is easily disrupted by excessive contact with the inside surface of the storage container. In addition, the retrieval of corneas which have settled to the bottom of storage vials is difficult as only an edge of 2 or 3 mm may contact the forceps without damaging the tissue.